The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Syd protest fails to stop asylum transfers

Tensions have flared outside a Sydney asylum seeker detention centre, where protesters were trying to stop 45 would-be refugees from being sent to Western Australia.

About 100 people had on Saturday gathered outside the Villawood facility, in Sydney's west, trying to "disrupt" the transfer of the asylum seekers to remote WA facilities in Curtin and Northam.

Three people who broke through a police barrier were detained for a short time and were later released without being charged, police told AAP.

The protest failed to stop the transfers, with two buses eventually leaving the centre at about 10.30am.

Protest spokeswoman Clo Schofield said transferring asylum seekers to remote parts of the country was an intentional move by the immigration department to isolate the detainees and to avoid public scrutiny of their conditions.

She said the eventual transfer was devastating and criticised the police for their heavy handed treatment of protesters.

Ms Schofield claimed a police dog had run free of its leash and attacked people at the rally.